As environmentally friendly vehicles, electrically powered vehicles have been drawing attention in recent years, such as electric vehicles, hybrid vehicles, and fuel cell vehicles. Each of these electrically powered vehicles has a motor for generating driving power for traveling, and a power storage device for storing electric power supplied to the motor. A hybrid vehicle refers to a vehicle having a motor and an internal combustion engine as motive power sources. A fuel cell vehicle refers to a vehicle having a fuel cell as a direct-current power source for driving the vehicle.
For such an electrically powered vehicle, a technique is proposed to charge the power storage device for driving the vehicle, by means of a commercial power source having high power generation efficiency. Particularly drawing attention is a technique of charging a power storage device mounted on an electrically powered vehicle, using a source of commercial electric power supplied to general houses (for example, a source of supplying a relatively low voltage of 100V or 200V).
As a charging system for such an electrically powered vehicle, SAE Electric Vehicle Conductive Charge Coupler (NPL 1) provides standard specifications for a vehicle inlet and a charging connector to facilitate shared usage of a charging cable and a connector among different vehicles.
SAE Electric Vehicle Conductive Charge Coupler defines, as an example, standard specification related to control pilot. The control pilot is defined as a control line connecting a control circuit of an EVSE (Electric Vehicle Supply Equipment) supplying electric power from premises wiring to the vehicle to the ground of the vehicle through control circuitry on the vehicle. Based on pilot signals communicated through this control line, state of connection of charging cable, whether or not power supply is possible from the power source to the vehicle, and rated current of EVSE are determined.